Information revealed during questioning at a Senate Estimates hearing indicates that the amount of oil leaking from the Montara wellhead may be much higher than the company's estimates.

Yesterday (Wed 21/10/09), under questioning by Greens’ Marine Issues Spokesperson Senator Rachel Siewert, Federal Department of Resources, Energy and Tourism officials said that PTTEP had given them no basis for their 400-barrels-day figure, and their own calculations based on Geoscience Australia data suggested a rate of around 2,000 barrels-a-day, plus condensate.

Using PTTEP’s own documents and data from similar wellheads nearby, independent analysis sourced by the Greens in the weeks following the spill calculated that the Montara wellhead may be leaking up to 3,000 barrels of oil-a-day into the Timor Sea off Australia’s north-west coast.

Despite requests by the Greens, there has been no explanation of the basis of this figure.

“It is clear that we can have no confidence in the estimates by the company and I must ask why the Government chose to support the company's estimates rather than the Department's estimates,” Senator Rachel Siewert said.

“It is clear a thorough and comprehensive inquiry is needed into this spill.

“If the oil had continued to leak at this rate over the two months since the accident on 21 August, this would suggest that up to 20 million litres of oil could have leaked into the Timor Sea.

“However, given the drop-off in the observed rate of oil leakage in the first weeks of the spill reported by AMSA, we might expect that the total amount of oil spilled could be lower, perhaps around 10 million litres.

“This puts the Montara oil spill clearly up there in the top three worst oil spills in Australia's history,” concluded Senator Siewert.